The spatial orientation of blanks and/or almost completely folded envelopes, called adjusting, is necessary in envelope production machines in order to precisely position the blanks for the purpose of the exact processing in a subsequent processing step. For example, if the following processing step comprises a folding process the adjusting must ensure that the fold occurs precisely along an already pre-pressed fold line.
A device for adjusting blanks is already known from DE 196 09 991 A1. It comprises a driver roller that can be impinged with a vacuum, arranged such that it can rotate coaxially between two stop roll bodies, which in turn are each provided with stop elements projecting in the radial direction. The driver roller rotates with a higher circumferential speed than the two synchronously rotating stop roll bodies. The blank to be oriented is caught by the vacuum effect of the driver roller and based on its higher circumferential speed it contacts the stop elements rotating at a slower speed. Here, the front edge of the blank is oriented from a potentially false position into one precisely perpendicular in reference to the transport direction.
The known device requires the impingement of the driver rollers with a vacuum, which is always connected to a certain expense. DE 196 09 991 A1 alternatively suggests to press the blanks to the driver roller via driver rollers. Such an embodiment leads in the device known that already oriented blanks are still pushed with the increased circumferential speed of the driver rollers, which can lead to malfunctions, such as a blank jam and consequently an interruption of production.
Another disadvantage of the device known from DE 196 09 991 A1 results from the tearing roll here being arranged relatively closely to the adjusting roll. This leads undesirably to the diameter of the adjusting roll having to be selected comparatively large in order to allow the orientation of large blanks and/or envelopes, which here must be located entirely on the perimeter of the adjusting roll. The next blank can only be separated from the scaled arrangement when the previous blank is located entirely on the perimeter of the adjusting roll.
From DE 10 2004 025 427 A1 a combined arrangement for accelerating and spatially orienting blanks is known.
In this arrangement as well, a driver roller body is used that can be impinged with a vacuum, which rotates with a higher circumferential speed than the two stop roll bodies allocated thereto. Alternatively it is suggested here to provide a transportation belt device instead of a driver roller body impinged with a vacuum, in which at least two transportation belts arranged over top of each other cooperate with each other such that they can entrain blanks by way of friction. Due to the sandwich-like clamping of the blank in this embodiment the already oriented blanks, contacting the stop elements with their front edges, have no liberty of movement to compensate the pushing motion of the two transport belts traveling at higher speeds. Such compensation requires slippage between the transport belts and the blanks, which on the one hand must meet the requirements of friction for the purpose of transportation and, on the other hand, may lead to undesired sliding tracks on the blanks.